This renewal application requests continued support for our postdoctoral training program in developmental genetics at The Jackson Laboratory (TJL). A primary theme of this training program, which was first funded in 1977, is use of the laboratory mouse as a model system for the study of human development, birth defects and disease. Sixteen TJL faculty members participate as mentors in this program. Research training areas include germ cell development, postimplantation embryonic development, neural and motor neuron development, epilepsy models, computational and systems biology, complex trait analysis, eye development and disease, control of genome stability, the relationship between gene expression and three-dimensional chromosome structure in the nucleus, and the developmental regulation of homeostatic mechanisms. These analyses are made possible by the availability of TJL's unparalleled resource base of more than 4,100 inbred, spontaneous and genetically-engineered mutant mice. Support is requested for three postdoctoral trainees. Trainees devote their major effort to laboratory research, but also receive training in scientific integrity, presentation skills, data analysis and grant writing. Trainees participate in TJL seminars, courses, workshops, and research interest groups. They are required to write fellowship applications, and present their results both at in-house interest groups and at national and international meetings. Their progress is overseen by a formal Training Committee, which evaluates new candidates for the program and monitors progress of the trainees annually. Each member of the Training Committee also acts as an informal mentor, or liaison, for several postdoctoral trainees at TJL. Upon completion of training, program participants are qualified to engage in creative, independent research in developmental genetics at a university, research institution, or in industry.